Process for preparing reactive stabilizing compound

ABSTRACT

Reactive stabilizing compounds, able to stabilize organic polymers, contain in their molecule a sterically hindered amino group and a hydrolyzable silyl function. In stabilizing organic polymers, said reactive stabilizing compounds can be hydrolyzed at the silyl function with the formation of silanol groups, which are made to interact in order to form complex resinous stabilizing structures. These latter are added in stabilizing quantities to the polymer to be stabilized. According to one particular embodiment, the hydrolysis at the silyl function and the formation of the resinous structure take place spontaneously within the polymer to be stabilized. According to a further embodiment, the reactive stabilizing compound is added to the polymer after being stably supported on a solid support by reaction with an inorganic solid having surface hydroxyl groups. According to a further embodiment, the reactive stabilizing compound is made to interact with the polymer so that the stabilizing compound becomes chemically bonded to the polymer chains. In all cases, stabilized polymers are obtained containing the stabilizing compound in a form which is not removable from the polymer. The processes for preparing the reactive stabilizing compounds and for preparing the stabilized polymer compositions are also described.

This is a divisional, of application Ser. No. 733,526 filed May 13,1985, now U.S. Pat. No. 4,684,726.

This invention relates to reactive stabilising compounds able tostabilise organic polymers, and also relates to the stabilised polymercompositions and the processes for preparing said stabilising compoundsand said stabilised polymer compositions. Organic polymers such aspolyolefins and polydienes are known to suffer degradation with thepassage of time due to exposure to atmospheric agents, and in particularto the action of ultraviolet radiation. This degradation manifestsitself as a worsening of the polymer physical characteristics, such as areduction in ultimate tensile stress and flexibility, these beingaccompanied by a change in the viscosity index.

In order to oppose this degradation, it is usual in industry toindroduce small quantities of stabilising compounds such asbenzotriazoles, benzophenones and nickel complexes into the polymers.Also known for this purpose are pyrrolidine derivatives described inU.S. Pat. Nos. 4,325,364 and 4,346,188 and organic compounds containingin their molecule at least one tetramethyl- or pentamethyl-morpholine,as described in the U.S. patent application Ser. No. 709,546 filed onMar. 8, 1985, now U.S. Pat. No. 4,617,333.

The problems encountered in stabilising organic polymers deriveessentially from the incompatibility between the stabilising compoundand the polymer, and from the release of the stabilising compound by thepolymer.

In stabilisation by means of known stabilising compounds, theseundesirable phenomena are manifested at a more or less considerablelevel, and there is therefore a need for stabilising compounds havinggreater compatibility with the polymers and able to permanently remaintherein.

It has now been found that such a requirement can be satisfied by thereactive stabilising compounds of the present invention, which containin their molecule a sterically hindered amino group and a hydrolysablesilyl function.

These reactive stabilising compounds can give rise to complex resinousstructures either within the polymer or outside it, or can bondchemically to the polymer or to a solid support. The result of theseinteractions is that structures are obtained which on the one handunexpectedly preserve the inherent stabilising characteristics of thesterically hindered amines, and on the other hand presentcharacteristics of compatibility with and permanence in the stabilisedpolymer which exceed those of the initial reactive stabilising compoundsand those of stabilising compounds known in the art.

Accordingly, one object of the present invention is constituted byreactive stabilising compounds containing in their molecule a stericallyhindered amino group and a hydrolysable silyl group. A further object ofthe present invention is constitued by processes for preparing saidreactive stabilising compounds. A further object of the presentinvention is constituted by polymer compositions stabilised by theproducts of the transformation of said reactive stabilising compounds atthe silyl function. A further object of the present invention isconstituted by processes for preparing said stabilised polymercompositions. Further objects of the invention will be more apparentfrom the description and experimental examples given hereinafter. Ingeneral, the reactive stabilising compounds of the present invention arecompounds containing the 2,2,6,6-tetramethylpiperidine group: ##STR1##or the 2,2,6,6-tetramethylmorpholine group: ##STR2## or the2,2,3,5,5-pentamethylpyrrolidine group: ##STR3## said groups carrying asilyl function which can be hydrolysed to silanol, and is connected to(I), (II) and (III) by a silicon-carbon bond.

More particularly, the reactive stabilising compounds of the presentinvention can pertain to the following classes of compounds: ##STR4##where:

m is zero or one;

R' is hydrogen or methyl;

Z is a group chosen from ##STR5## (where R₁ is a linear or branchedalkyl radical containing from 1 to 5 carbon atoms);

R is a linear or branched alkylene radical containing from 1 to 10carbon atoms, or is representable by: ##STR6## (where R₂ and R₃ arelinear or branched alkylene radicals containing a total of between 2 and10 carbon atoms);

X is a linear or branched alkyl radical containing from 1 to 5 carbonatoms, and preferably the methyl radical;

Y is hydrogen, halogen and preferably chlorine, C₁ -C₄ acyloxy, C₁ -C₄alkyloxy, amino, amino-oxy or silyloxy, and preferably C₁ -C₂ alkyloxy;

n is one, two or three.

Specific examples of reactive stabilising compounds which fall withinformula (IV) are as follows: ##STR7##

The reactive stabilising compounds (VII), (VIII), (IX) and (X) can beobtained starting from the compound ##STR8## by silylation withmethyldiethoxysilane, triethyloxysilane, dimethylchlorosilane andtetramethyldisiloxane respectively. Further specific examples ofreactive stabilising compounds which fall within formula (VI) are thefollowing; ##STR9##

The reactive stabilising compounds (XII), (XIII) and (XIV) can beobtained from the compound: ##STR10## by silylation withmethyldiethoxysilane, triethoxysilane andγ-mercaptopropyltrimethoxysilane respectively.

A specific example of a compound which falls within general formula (V)is the following: ##STR11##

The reactive stabilising compound (XVI) can be obtained by silylation ofthe compound: ##STR12## with γ-mercaptopropyltrimethoxysilane.

A specific example of a further compound which falls within generalformula (V) is the following: ##STR13##

The reactive stabilising compound (XVIII) can be obtained by silylationof the compound: ##STR14## with triethoxysilane.

A specific example of a compound which falls within general formula (VI)is the following: ##STR15##

The reactive stabilising compound (XX) can be obtained by silylation ofthe compound: ##STR16## with triethoxysilane.

In general, the reactive stabilising compounds of the present inventioncan be prepared by silylating a 2,2,6,6-tetramethylpiperidine, or a2,2,6,6-tetramethylmorpholine, or a 2,2,3,5,5-pentamethylpyrrolidinewhich carry on their ring a preferably terminal, alkylenicallyunsaturated bond.

One class of silylation agents suitable for this purpose can be definedby the general formula: ##STR17## where X, Y and n have the aforesaidmeanings.

Specific examples of silylation agents which fall within formula (XXII)are the following:

HSi(CH₃)₂ Cl; HSi(CH₃)Cl₂ ; HSiCl₃ ; HSi(CH₃)(OCH₃)₂ ; HSi(CH₃)(OC₂ H₅)₂; HSi(OC₂ H₅)₃ ; H₂ Si(C₂ H₅)₂ ; HSi(OCH₃)₃ ; HSi(CH₃)₂ OSi(CH₃)₂ H;HSi(CH₃)₂ OSi(CH₃)(OCH₃)₂ ; HSi(CH₃)₂ ONC(CH₃)₂ ; HSi(CH₃)₂ N(CH₃)₂ ;HSi(CH₃)(OCOCH₃)₂ ; HSi(CH₃)[ONC(CH₃)₂ ]₂.

The silylation reaction is conveniently conducted at a temperature ofbetween 0° and 200° C., and preferably between ambient temperature(20°-25° C.) and 120° C., with a reagent quantity varying fromstoichiometric to an excess of the silylation agent. Said excess usuallyreaches up to 20% on a molar basis. However, if disilanes are used it isconvenient to use a large excess of the silylation agent, for example upto 10 times the stoichiometric value.

The silylation reaction is catalysed by metal catalysts, by ultravioletradiation and by radical initiators. The preferred catalysts areplatinum compounds and complexes of platinum with olefins, in particularchloroplatinic acid. In the case of platinum catalysts, the catalystconcentration, evaluated as metal, can vary from 1 to 200 parts permillion and preferably from 5 to 50 parts per million in the reactionmedium.

The silylation reaction can be conducted in an inert (unreactive)organic solvent, normally chosen from aliphatic, cycloaliphatic andaromatic hydrocarbons and ethers, which are liquid under the operatingconditions. Specific examples of solvents suitable for this purpose areheptane, cyclohexane, toluene, tetrahydrofuran, dioxane anddimethoxyethane.

The reaction times depend on the particular reagents used and thereaction temperature, and vary normally from 0.5 to 10 hours. Ontermination of the silylation reaction, any solvent used and any excesssilylation agent are removed by stripping, and the reactive stabilisingcompound is recovered from the residue of said stripping by normalmethods such as crystallisation and distillation under vacuum.

However, generally the high yield and selectivity of the silylationreaction make any separation or purification of the final requiredproduct unnecessary. A further class of silylation agents suitable forthe purpose can be defined by the general formula: ##STR18## where R₃,X, Y and n have the aforesaid meanings.

Specific examples of silylation agents falling within formula (XXIII)are γ-mercaptopropyltrialkoxysilanes, and in particularγ-mercaptopropyltrimethoxysilane.

If silylating compounds falling within formula (XXIII) are used, thereaction can be conducted under the aforesaid general silylationconditions, in the presence of catalysts of radical or ionic type, orunder the action of ultraviolet radiation. In this case the preferredcatalysts are azo compounds, such as azobisisobutyronitrile, which areconveniently used in a quantity of between 0.1% and 10% and preferablybetween 0.5% and 2% in the reaction environment. The reactivestabilising compounds of the present invention hydrolyse at the silylfunction, under mild conditions, to generate silanol groups which can becondensed together to form complex resinous stabilising structures.

These resinous structures, of silicone resin type, preserve the inherentstabilising characteristics of sterically hindered amines, and have avery high level of compatibility with organic polymers, and practicallyno extractability from such polymers. Hydrolysis of the silyl functiontakes place simply by contact with water or with environmental moistureat ambient temperature (20°-25° C.) or lower than ambient.

Condensation between the silanol groups to give the complex resinousstructures can be facilitated by acid or basic agents, soaps and metalesters, and organometal compounds, especially of zinc, lead and tin.

Catalysts suitable for this purpose are zinc octoate, lead naphthenateand tin dibutyl-laurate. Conveniently, the catalyst quantity can varyfrom 0.1% to 10% by weight and preferably from 0.2% to 3% by weight withrespect to the reactive stabilising compound subjected toresinification. Said resinification reaction can be conducted at ambienttemperature (20°-25° C.) or at higher or lower than ambient. The complexresinous structure thus obtained can be introduced into the organicpolymer to be stabilised by the usual methods used for this purpose.

According to a further embodiment of the present invention, the reactivestabilising compounds are introduced directly into the organic polymer,within which the hydrolysis reaction at the silyl function and theinteraction between the silanol groups take place spontaneously, to thusgive the stabilised polymer composition. According to a furtherembodiment, hydrolysis at the silyl function of the reactive stabilisingcompounds takes place externally to the polymer, together with partialresinification of the hydrolysis products thus obtained. The product ofthe partial resinification is then introduced into the organic polymerto be stabilised, within which complete resinification takes place.

According to a preferred embodiment, the reactive stabilising compoundsof the present invention are reduced to pigment form, and as such areadded to the organic polymer to be stabilised. For this purpose, thereactive stabilising compounds are hydrolysed and resinified by exposureto moisture, possibly in the presence of a catalyst chosen from thosedescribed heretofore. The resinification products thus obtained, in theform of vitreous solids and still soluble in aliphatic alcohols, areheated to a temperature exceeding 100° C. and generally of between 120°and 220° C. for a time of between 10 minutes and 6 hours. After cooling,the solid is ground and pulverised, and the powder thus obtained isadded to the organic polymer to be stabilised. According to a furtherembodiment of the present invention, the reactive stabilising compoundsare added to silicone varnishes, such as those available commercially,generally in a hydrocarbon vehicle and co-resinified together with saidvarnishes, using the actual heat treatment of the varnishes. Theresultant vitreous products are ground and pulverised and the powder isadded to the organic polymer to be stabilised. In this latterembodiment, a quantity of reactive stabilising compound of between 10%and 90% by weight with respect to the silicone varnish can be used. Inall cases, the powders added to the polymer to be stabilised should havea size of less than 10 microns and preferably of the order of 0.1-2microns.

The structure of these resinification products depends essentially onthe number of groups hydrolysable at the silyl function in the reactivestabilising compounds.

For example in the case of compound (IX), which contains only onehydrolysable group, the hydrolysis and resinification reactions proceeduntil a dimer is produced, which in the case in question can be definedby the following formula: ##STR19## In the case of compounds with two orthree hydrolysable groups in the silyl function, more complexresinification products are obtained, in the form of linear andthree-dimensional polymer chains respectively.

The reactive stabilising compounds of the present invention can be fixedto a solid support containing surface hydroxyl groups. Supports suitablefor this purpose are siliceous materials, of either natural or syntheticorigin, such as diatomaceous earth, celite, silica gel, cement, glass,glass fibers and silicon aluminates in general. The preferred of allthese supports is that type of silica commonly known as fumed silicawhich, together with good optical characteristics, has low apparentdensity, a high specific surface (generally exceeding 200 m² /g) and ahigh surface concentration of hydroxyl groups.

The bond to the support is produced by reacting the reactive stabilisingcompound in its hydrolysed form with the surface hydroxyl groups of thesupport. In practice, the support, in the form of powder or granules, isput into contact with a solution of the reactive stabilising compound inan inert organic solvent, such as an aliphatic cycloaliphatic oraromatic hydrocarbon or an ether. The procedure is carried out in theliquid phase at a temperature between ambient (20°-25° C.) and about100° C. The reactive stabilising compound becomes hydrolysed and bondedto the support within a time of the order of between 0.5 and 10 hours.

The stabilising compound thus supported is added to the organic polymerto be stabilised, by normal methods. This embodiment has the furtheradvantage of excellent distribution of the stabilising compound in thepolymer.

According to a further embodiment, the reactive stabilising compounds ofthe present invention are bonded chemically to the organic polymer to bestabilised. This method is particularly effective in the case ofdiolefinic polymers and copolymers of low molecular weight. The reactionbetween the reactive stabilising compound and the polymer generallytakes place at a temperature of between ambient (20°-25° C.) and about100° C., in the presence of an inert (unreactive) diluent, in a time ofbetween 0.5 and 10 hours.

The reactive stabilising compounds of the present invention are able tostabilise organic polymers in general, and in particular homopolymersand copolymers of olefins and diolefins such as polypropylene,polybutadiene and polyethylene of high and low density, especiallytowards ultraviolet radiation.

The stabilised polymer compositions of the present invention contain astabilising quantity of the described stabilising compounds. Inparticular, the stabilising quantity of a stabilising compound is thatwhich adds to the composition at least 0.003% by weight of activenitrogen, the term "active nitrogen" signifying the nitrogen in thepiperidine, morpholine or pyrrolidine ring. There is no critical upperlimit to the quantity of stabilising compound present in thecomposition, however it is preferable to not exceed 0.03% by weight ofactive nitrogen, both for economy reasons and in order not to causeundesirable changes in one or more characteristics of the organicpolymer.

In the preferred embodiment, the polymer compositions of the presentinvention contain an active nitrogen quantity of between 0.005% and0.02% by weight, the absolutely preferred values being of the order of0.010%-0.015% by weight. The following experimental examples are givenfor illustrative purposes, and do not limit the range of the invention.

EXAMPLE 1 Preparation of compound (XI): ##STR20##

Dimethoxyethane (200 ml), tetramethylpiperidinol (47.1 g; 22.6 moles)and metal potassium (13 g; 0.325 g atoms) are fed under a stream ofanhydrous nitrogen into a four-neck flask provided with an agitator,thermometer, dropping funnel and reflux condenser.

The suspension is heated under slight reflux for 16 hours underagitation. At the end of this time, not all the potassium has reacted.

The mixture is cooled to 50° C., and allyl bromide (28.6 ml; 4.00 g;0.33 moles) is slowly added through the dropping funnel, whilemaintaining the temperature between 50° and 60° C. When the addition iscomplete, the mass is kept under slight boiling for 30 minutes. A whiteprecipitate of potassium bromide is formed, which is kept in suspension.After said time, a small quantity of methanol (5 ml) is added toeliminate any presence of unreacted metal potassium. After cooling, thesuspension is filtered through a sintered glass filter and the separatedpotassium bromide is washed with 3×50 ml portions of dimethoxyethane.

The liquid wash fractions and the filtrate are pooled and subjected tofractional distillation under vacuum (1 torr) to give the compound (XI)(40.5 g; yield 68.5% evaluated on the fed tetramethylpiperidinol). Thecompound (XI) thus obtained has a boiling point of 56°-58° C.

    ______________________________________                                        Elementary analysis                                                           ______________________________________                                        theoretical  C     73.1%    H   11.7%  N   7.1%                               found        C     73.0%    H   11.5%  N   7.0%                               ______________________________________                                    

EXAMPLE 2 Preparation of compound (VII): ##STR21## The compound (XI)(9.85 g; 50 mmoles) is reacted in a closed vessel withmethyldiethoxysilane (8.73 g; 10.5 ml; 65 mmoles) in the presence oftraces of chloroplatinic acid dissolved in isopropanol (20 μl of a 2weight % solution of H₂ PtCl₆.6H₂ O).

The reaction is conducted under agitation at 75° C. for 4 hours and at100° C. for one hour. At the end of this time, spectroscopic examinationshows that the compound (XI) has completely reacted (disappearance ofthe band at 1645 cm⁻¹). The reaction mixture, of oily appearance, istransferred into a Claisen apparatus, the excess dimethyldiethoxysilaneis stripped off under vacuum, and fractionation is carried out toseparate 12.7 g of compound (VII) [yield 77% with respect to compound(XI)], having a boiling point of 127°-130° C. (1 torr) and [n]_(D) ²⁰=1.4439.

    ______________________________________                                        Elementary analysis                                                           ______________________________________                                        theoretical  C     61.6%    H   11.2%  N   4.2%                               found        C     62.2%    H   11.2%  N   4.2%                               ______________________________________                                    

The structure of the compound (VII) is confirmed by mass spectroscopy(M⁺ 331) and IR and ¹ Hnmr analysis.

EXAMPLE 3 Preparation of the compound (VIII): ##STR22## The compound(XI) (5.91 g; 30 mmoles) is reacted with triethyloxysilane (6.6 g; 7.5ml; 40.0 mmoles) in the presence of traces of chloroplatinic acid inaccordance with the procedure of Example 2. On fractionating thereaction product under reduced pressure, 7.2 g of the compound (VIII)are obtained [yield 66.5% with respect to the compound (XI)], having aboiling point of 136°-138° C. (1 torr).

    ______________________________________                                        Elementary analysis                                                           ______________________________________                                        theoretical  C     59.8%    H   10.8%  N   3.9%                               found        C     60.0%    H   10.8%  N   3.8%                               ______________________________________                                    

The structure of the compound (VIII) is confirmed by mass spectroscopy(M⁺ 361) and IR and ¹ Hnmr analysis.

EXAMPLE 4 Preparation of the compound (IX) ##STR23## The compound (XI)(4.0 g; 22.3 mmoles) is reacted with dimethylchlorosilane (2.85 g; 34mmoles) in the presence of traces of chloroplatinic acid in accordancewith the procedure of Example 2. The reaction mixture thus obtained isstripped under reduced pressure and the resultant oily residue (about5.5 g) shows no presence of the allyl unsaturation band at 1645 cm⁻¹ onIR analysis. The mass spectrum (M⁺ 291) and elementary analysis(chlorine content 11.7% by weight-theoretical value 12.2% by weight)confirm the structure of the compound (IX) which is used without furtherpurification. EXAMPLE 5 Preparation of the compound (XXIV) ##STR24## byhydrolysis and resinification of the compound (IX). The compound (IX),obtained in the preceding Example 4 (4.0 g; 13.6 mmoles) is diluted withdiethyl ether, and ice (about 10 g) is added, operating in a flaskprovided with a magnetic bar agitator. After liquefaction of the ice,the water and organic phases are agitated for two hours at ambienttemperature. The ether layer is then separated, washed with aqueoussodium bicarbonate and water, and dried under vacuum to remove thediethyl ether. 1.7 g of an oily residue are obtained in this manner,which on elementary analysis shows the following values: C 62.9%, H11.5%; N 5.1%; Cl absent.

The theorethical values for the compound (XXIV) are C 63.6%; H 6.4%; N5.3%. The mass spectrum does not produce the parent ion, but IR and ¹Hnmr analysis confirm the structure of the compound (XXIV). The aqueouslayer is extracted with 2×30 ml portions of chloroform, to allow therecovery of 1.8 g of a product constituted mostly by the compound(XXIV), the remainder consisting of unidentified compounds.

EXAMPLE 7 Preparation of the compound (XII): ##STR25##

The compound (XV): ##STR26## (5.0 g; 19.8 mmoles) is reacted under theconditions of Example 1 with methyldiethoxysilane (3.4 g; 4.1 ml; 25mmoles). The completeness of the reaction is verified by IR analysis onthe basis of the total disappearance of the band at 1638 cm⁻¹ (allylband). Fractional distillation under reduced pressure results in theseparation of 6.2 g of an oily material [yield 82.4% with respect to thecompound (XV)] having a boiling point of 142°-144° C. (1 torr), andconsisting of the compound (XII).

    ______________________________________                                        Elementary analysis                                                           ______________________________________                                        theoretical  C     65.3%    H   11.9%  N   7.3%                               found        C     65.1%    H   11.9%  N   7.3%                               ______________________________________                                    

The mass spectrum (M⁺ 386) and IR and ¹ Hnmr analysis confirm thestructure of the compound (XII).

EXAMPLE 8 Preparation of the compound (XIII): ##STR27## The compound(XV) (6.3 g; 25.0 mmoles) is reacted under the conditions of Example 1with triethoxysilane (5.6 ml; 4.3 g; 30 mmoles) for 6 hours at 100° C.and for the next 2 hours at 120° C. The reaction mixture is thentransferred into a Claisen apparatus and is distilled under vacuum (1torr) to give 5.3 g of a colourless oil [yield 51% with respect to thecompound (XV)], having a boiling point of 147°-149° C. (1 torr) andconsisting of the compound (XIII).

    ______________________________________                                        Elementary analysis                                                           ______________________________________                                        theoretical  C     63.5%    H   11.5%  N   6.7%                               found        C     63.0%    H   11.3%  N   6.2%                               ______________________________________                                    

The mass spectrum (M⁺ 416) and IR and ¹ Hnmr analysis confirm thestructure of the compound (XIII).

EXAMPLE 9 Preparation of the compound (XIV) ##STR28## The compound (XV)(3.5 g; 13.8 mmoles) is reacted with slightly more than thestoichiometric quantity of δ-mercaptopropyltrimethoxysilane (3.3 g; 3.2ml; 17.0 mmoles), together with azobisisobutyronitrile (130 mg)dissolved in 4 ml of toluene, in a flask fitted with a magneticagitator.

The mixture is agitated for 4 hours at 85° C. and then for the next hourat 110° C. After cooling, the reaction mixture is distilled in a bulbstill under reduced pressure (1 torr), and the fraction which distils ata boiler temperature of 230°-235° C. (1 torr) is collected. 3.1 g of acolourless oil are recovered [yield 50% with respect to the compound(XV)], consisting of the compound (XIV).

    ______________________________________                                        Elementary analysis                                                           ______________________________________                                        theoretical  C     58.9%    H   10.7%  S   7.1%                               found        C     60.1%    H   10.8%  S   6.8%                               ______________________________________                                    

The mass spectrum (M⁺ 448) and IR and ¹ Hnmr analysis confirm thestructure of the compound (XIV).

EXAMPLE 10 Preparation of the compound (XVI) ##STR29##

The compound (XVII) ##STR30## (6.3 g; 40.6 mmoles) is reacted withδ-mercaptopropyltrimethoxysilane (9.8 g; 9.4 ml; 50 mmoles) under theconditions of the preceding Example 9. The reaction mixture is strippedat 60° C. under reduced pressure, and the residue is distilled in a bulbstill and the fraction which distils at a boiler temperature of185°-190° C. (1 torr) is collected. 6.2 g of an oil consisting of thecompound (XVI) are recovered.

    ______________________________________                                        Elementary analysis                                                           ______________________________________                                        theoretical C     51.3%   H   9.4% N   4.0% S   9.1%                          found       C     50.8%   H   9.4% N   3.9% S   9.1%                          ______________________________________                                    

The mass spectrum (M⁺ 351) and IR and ¹ Hnmr analysis confirm thestructure of the compound (XVI).

EXAMPLE 11 Preparation of the hydrolysis and resinification product ofthe compound (VII).

The compound (VII) (3 g; 9.1 mmoles) is placed in a watch glass togetherwith 30 μl of Sn(n-C₄ H₉)₂ (laurate)₂.

The glass with its contents is then placed in a controlled-humidityenvironment (50% relative humidity) at ambient temperature (about 20°C.) for one week.

At the end of this period, the IR spectrum of the product obtainedappears substantially changed compared with that of the startingcompound (VII). Attempts at distillation with a boiler temperature of230°-240° C. (1 torr) did not separate any appreciable quantity ofvolatile products.

EXAMPLE 12 Deposition of the compound (VII) on a fumed silica support.50 g of anhydrous fumed silica (a commercial product of the firm Wacker)with a specific surface of 250 m² /g and apparent density of 0.05 g/mlare placed in 150 ml of boiling n-heptane containing 0.5 g of thecompound (VII), the mixture being heated under reflux for 4-5 hours. Atthe end of this period, the reaction mixture is cooled, filtered, thefiltered solid washed with n-pentane, and the washed solid then dried.IR examination of the obtained solid in hexachlorobutadiene shows thepresence of a supported organic material, which is not removed bywashing with liquid hydrocarbons. The liquid n-pentane and n-heptanefractions are pooled and evaporated to dryness under reduced pressure.0.140 g of an oily residue are obtained. On the basis of these resultsit is assumed that about 70% of the compound (VII) was stably supportedon the fumed silica. EXAMPLE 13 Preparation of the compound (X):##STR31## The compound (XI) (1.3 g; 6.6 mmoles) is reacted withtetramethyldisiloxane (8.86 g; 11.7 ml; 66 mmoles) in the presence ofchloroplatinic acid in a manner similar to Example 2.

The operation is carried out in an iso-octanol environment at 80° C. for4 hours. At the end of this period, the reaction mixture is strippedunder reduced pressure to remove the iso-octanol and the excesstetramethyldisiloxane, to give a residue of 2.1 g of the oily compound(X) having a boiling point of 100°-102° C. (0.5 torr), with a Si--H band(IR) at 2120 cm⁻¹.

EXAMPLE 14 Grafting the compound (X) onto liquid polybutadiene.

The compound (XI) (1.0 g; 3.0 mmoles) in 10 ml of cyclohexane is addedto a commercial liquid polybutadiene of molecular weight 2400 and vinylcontent 18.7% (14.4 g; 6 mmoles).

The mixture is heated for 6 hours to 100° C. without adding catalyst. Atthe end of this period, IR examination shows the absence of Si--H bonds(absence of the band at 2138 cm⁻¹) and the consequent bonding of thecompound (X) to the liquid polybutadiene.

EXAMPLE 15

An alternative method for producing the compound (XXIV) consists ofreacting the compound (VIII) with1,1,2,2-tetramethyl-1,2-dihydrodisiloxane in the presence of a platinumcatalyst.

The compound (VIII) (4.0 g; 20 mmoles) and1,1,2,2-tetramethyl-1,2-dihydrosiloxane (1.34 g; 1.72 ml; 10 mmoles) arereacted at 85° C. in the presence of 10 μl of the catalyst described inExample 2. After a further hour at 100° C., the reaction is complete(disappearance of the Si--H band at 2130 cm⁻¹ on IR analysis). Afterstripping the product under reduced pressure (0.1 torr; 120° C.), 5.2 gof a residue are obtained (yield 97%) in the form of an undistillableoil, constituted by the compound (XXIV).

EXAMPLE 16 Preparation of the compound (XXI): ##STR32##2,2,3,5,5-pentamethyl-4-methylolpyrrolidine (3,1 g; 21.0 mmoles) isreacted with metal potassium (0.88 g; 22.0 m atoms) in dimethoxyethane(50 ml) under reflux for 10 hours.

At the end of this period, the potassium is still present in anunaltered state.

The reaction mixture is cooled to 60° C., and allyl chloride (1.91 g;2.1 ml; 25.0 mmoles) is carefully added over about 5 minutes. Afterreacting at 60° C. for one hour, a suspension is obtained and isfiltered off through sintered glass, the dimethoxyethane is eliminatedby evaporation under reduced pressure at ambient temperature, and theoily residue is distilled under reduced pressure to give 3.3 g of thecompound (XXI) (yield 79%; boiling point 58°-60° C., 0.5 torr). Thestructure of the compound (XXI) is confirmed by mass spectroscopy (M⁺197) and IR and ¹ Hnmr analysis.

    ______________________________________                                        Elementary analysis                                                           ______________________________________                                        theoretical  C     73.1%    H   11.7%  N   7.1%                               found        C     71.8%    H   11.5%  N   6.9%                               ______________________________________                                    

EXAMPLE 17 Preparation of the compound (XX): ##STR33## The compound(XXI) (2.5 g; 12.7 mmoles) is reacted at 135° C. with triethoxysilane(2.47 g; 2.8 ml; 15.0 mmoles) for 4 hours in the presence of 10 μl ofthe catalyst described in Example 2.

On termination of the reaction, the resultant oil is distilled to obtaina fraction having a boiling point of 130°-133° C. at 0.5 torr, andconstituting the required compound (XX) (2.8 g; yield 62%). Thestructure of the compound (XX) is confirmed by mass spectroscopy (M⁺361) and IR and ¹ Hnmr analysis.

    ______________________________________                                        Elementary analysis                                                           ______________________________________                                        theoretical  C     60.3%    H   10.8%  N   3.8%                               found        C     59.8%    H   10.8%  N   3.9%                               ______________________________________                                    

EXAMPLE 18 Preparation of the compound (XIX): ##STR34##2-methylenetetramethylmorpholine (4.1 g; 26.5 mmoles) and ethyleneglycolmonoallylether (2.7 g; 26.5 mmoles) are agitated at 110° C. for 3 hoursin the presence of p-toluenesulphonic acid (0.1 g; approximately 1.5% byweight in the reaction mixture). The resultant product is fractionatedunder vacuum to give the compound (XIX) (4.2 g; yield 62%), with aboiling point of 86°-88° C. at 0.5 torr. The structure of the compound(XIX) is confirmed by mass spectroscopy (M⁺ 257) and IR and ¹ Hnmranalysis.

    ______________________________________                                        Elementary analysis                                                           ______________________________________                                        theoretical  C     65.6%    H   10.5%  N   5.4%                               found        C     65.4%    H   10.5%  N   5.4%                               ______________________________________                                    

EXAMPLE 19 Preparation of the compound (XVIII) ##STR35## The compound(XIX) (3.5 g; 13.6 mmoles) is reacted with triethoxysilane (2.55 g; 2.8ml; 15.5 mmoles) at 120° C. for 6 hours in the presence of 10 μl of thecatalyst described in Example 2. The reaction products are thendistilled to give a fraction having a boiling point of 120°-125° C. at0.5 torr, and constituted by the required compound (XVIII) (0.7 g; yield12%). The structure of the compound (XVIII) is confirmed by massspectroscopy (M⁺ 421) and by IR and ¹ Hnmr analysis.

    ______________________________________                                        Elementary analysis                                                           ______________________________________                                        theoretical  C     58.1%    H   10.7%  N   3.1%                               found        C     57.0%    H   10.2%  N   3.3%                               ______________________________________                                    

EXAMPLE 20

The compound (VIII) (3.5 g) is added to a commercial silicone varnish(DOW CQS-6312) containing 35% of solids in hydroalcoholic solution (18.6g), the procedure being carried out in a flat-bottomed aluminium capsuleof diameter 10 cm, which is then left standing overnight in theenvironmental atmosphere. The capsule is then heated to 35° C. for 4hours in an oven to give a transparent glass, which is finally dried inan oven at 130° C. for 4 hours.

The vitreous flakes obtained (8.3 g) are pulverised in a vibration millto give a white powdery material in which more than 80% of the particleshave a diameter equal to or less than 1 micron.

The stabilising action of the stabilising compounds of the presentinvention is verified by laboratory tests capable of simulating olefinicpolymer degradation. Specifically, propylene films to which thestabilising compounds have been added are subjected to UV radiation in aphotochemical reactor temperature-controlled at 80° C. In this manner,the sample is subjected both to thermal and to photodegradationstresses, during which the oxygen absorbed by the film is measuredagainst time. The specific apparatus used is constituted by:

a radiation reactor provided with a high-pressure 150 watt mercuryvapour lamp emitting light at λ≧300 nm;

a balancing chamber of the same temperature as the reactor, to preventvolume variations due to temperature changes;

a U tube containing mercury and fitted with electric contacts, itspurpose being to activate the motor which controls the advancement ofthe plunger of a temperature-controlled syringe containing oxygen. Withthis system, the absorption of oxygen with time is observed by followingthe motion of the plunger. The time required for the absorption ofoxygen to begin is known as the induction time (To). The test iscontinued until 10 ml of oxygen have been absorbed by the sample, andthe corresponding time is indicated by (T₁₀ -To). The greater theinduction time, the slower is the oxygen consumption, and the morestable is the stabilised polypropylene.

The films used for the test are prepared by dissolving the stabilisingcompound in benzene and mixing the resultant solution with the powderedpolypropylene. The polypropylene is free from any other additive. Thesolvent is then eliminated by evaporation under reduced pressure, andthe resultant powder is pressed into a film having a thickness of about100 μm, operating at 150° C. and 900 kg/cm², for a time of 2 minutes.

The film is extracted from the press and is cooled rapidly under runningwater.

Table 1 shows the induction times and the times for absorbing 10 ml ofoxygen, both for polypropylene as such and for the polypropylene towhich the stabilising compounds XII, VII, VIII and XIV have been addedin such quantities as to produce an active nitrogen content of 0.015% byweight in the polymer.

For comparison purposes, films are tested containing the commercialproducts TINUVIN 770 and CHIMASSORB 944 in such quantities as to againproduce an active nitrogen content of 0.015% by weight in the polymer,and also films containing the commercial product CYASORB 5411 in aquantity of 0.5% by weight in the polymer.

                  TABLE 1                                                         ______________________________________                                                                 Time for consuming                                                Induction time                                                                            10 ml of O.sub.2                                     Additive     (To) (minutes)                                                                            (T.sub.10 -To) (minutes)                             ______________________________________                                        None          480         1550                                                CHIMASSORB 944                                                                             5000         8500                                                TINUVIN 770  7000        16000                                                CYASORB 5411 1300         1800                                                COMPOUND XII 5000        13500                                                COMPOUND VII 8000        19500                                                COMPOUND VIII                                                                              8000        19500                                                COMPOUND XIV 8500        20000                                                ______________________________________                                    

As heretofore described, the reactive stabilising compounds of thepresent invention can give rise to resinification reactions, or can beanchored to a support or to the polymer to be stabilised, and thesecharacteristics can be utilised in order to enhance the permanence ofthe stabiliser in the polymer, both during its processing, and duringits working life.

The resinification or support-anchoring phenomena, which result in anincrease in the permanence of the additive in the polymer, are tested bycomparing the stationary concentration of the nitroxyl radical, obtainedby oxidising the sterically hindered amino group of the stabilisingcompound molecule, and measured by ESR spectra taken directly on thepolymer samples, to which the stabilising compound has been added eitherin monomer form, or in resinified form, or supported form, and thenheating for some hours to 170° C. Specifically, the formation of thenitroxyl radical takes place directly in the polypropylene film byphoto-sensitised oxidation with singlet oxygen. The polypropylene filmis obtained as described heretofore. The quantity of stabilisingcompound introduced into the polymer is 0.15% by weight of the polymer.The photo-sensitiser able to produce singlet oxygen (Rose Bengal,chlorophyll) is added in a quantity of 0.1% by weight with respect tothe polymer.

The film is then subjected to UV radiation for 18 hours by ahigh-pressure 150 watt mercury vapour lamp coupled to a UV 31 filterwhich provides a passing band of radiation of λ≧290 nm. Afterirradiating a weighed portion of the film, a check is carried out by ESRspectra of the formation of the radical and its persistence in thesample at the temperature of 170° C. Table 2 shows the test results.

                  TABLE 2                                                         ______________________________________                                                              Reduction in the radical                                                      concentration after 5 hours of                               Stabilising      heating to 170° C. (% with                       Test compound         respect to initial concentration)                       ______________________________________                                        A    COMPOUND VIII    90%                                                     B    COMPOUND VIII plus                                                                             60%                                                          tin diacetate                                                            C    COMPOUND VIII plus                                                                             30%                                                          tin diacetate                                                            D    COMPOUND VIII plus                                                                             30%                                                          tin diacetate                                                            E    COMPOUND VII     87%                                                     F    COMPOUND VII     15%                                                          (4 wt % on silica)                                                       ______________________________________                                    

Specifically, in tests A and E the stabilising compounds VIII and VIIare added respectively in the monomer form to the powdered polymer.

In test B the compound VIII is added to the powdered polypropylenetogether with the tin diacetate. In test C the procedure is as in testB, but heating the polypropylene film for 1 hour to 80° C. in distilledwater.

In test D the compound VII is resinified externally to the polypropylenein the presence of tin diacetate in a saturated water vapourenvironment. The resinification product thus obtained is dissolved inalcohol, and the solution is added to the powdered polypropylene.

The alcohol is then removed by evaporation under reduced pressure, andthe residual powder is pressed as heretofore described. In test F, thecompound VII anchored to the silica is homogenised with thepolypropylene by grinding in a ball mill.

We claim:
 1. A process for preparing reactive stabilizing compoundshaving one of the following formulas: ##STR36## wherein; m is 1;Z isselected from ##STR37## X is selected from a linear or branched alkylgroup having from 1 to 5 carbon atoms; Y is selected from hydrogen,halogen, C₁ -C₄ acyloxy, C₁ -C₄ alkyoxy, amino, aminooxy or silyloxy;and n is an integer selected from one, two or three comprising, reactinga compound of the formula: ##STR38## with a silylating agent selectedfrom compounds of the formula ##STR39## wherein X and Y have the samemeaning as above.
 2. The process of claim 1 wherein Y is hydrogen. 3.The process of claim 1 wherein X is methyl and Y is selected fromchlorine and C₁ -C₄ alkyloxy.
 4. The process of claim 1 wherein thestabilizing compound has the formula ##STR40##
 5. The process of claim 1wherein the stabilizing compound has the formula ##STR41##
 6. Theprocess of claim 1 wherein the stabilizing compound has the formula##STR42##
 7. The process of claim 1 wherein the stabilizing compound hasthe formula ##STR43##
 8. The process of claim 1 wherein the stabilizingcompound has the formula ##STR44##
 9. The process of claim 1 wherein thestabilizing compound has the formula ##STR45##
 10. The process of claim1 wherein the stabilizing compound has the formula ##STR46##
 11. Theprocess of claim 1, wherein said silylating agent is selected frommethyldiethoxysilane, triethoxysilane, dimethylchlorosilane, andtetramethyldisiloxane.
 12. The process of claim 1, wherein the reactionis conducted at a temperature of between 0° and 200° C. with at least astoichiometric amount of the silylating agent, in the presence of acatalyst selected from metal catalysts, ultraviolet radiation andradical initiators, for between 0.5 and 10 hours.
 13. The process ofclaim 12, wherein the reaction is conducted at a temperature betweenambient temperature and 120° C., with a platinum containing catalyst ora complex of platinum with olefins, in a quantity, expressed as metal,of between 1 and 200 parts per million in the reaction medium, in thepresence of an inert organic solvent selected from aliphatic,cycloaliphatic and, aromatic hydrocarbons and ethers.